Meeting Abstract
Fish scales interact with the external environment and have evolved to meet the physical demands of the animal, including attacks from predators. Flatfishes are unusual because they have left-right asymmetry of their bodies (eyed vs. blind sides), and the two sides may be under different selective pressures. We used three species of flatfish (Parophrys vetulus, Isopsetta isolepis and Platichthys stellatus) from different habitats (soft-bottomed vs. gravel) to address questions related to resistance to puncture force (a proxy for predator attack or environmental insult). Is the force required to puncture the scales similar across species? Does puncture force differ between the eyed and blind sides? How does puncture force change as fish grow larger? We predicted that Platichthys would require the greatest force to puncture the scales+skin because the species is less cryptic, can be found on a gravel substrate, and has the largest scales of the three species. In addition, we predicted that the eyed side of each species would require a larger puncture force because it is more exposed to the environment and potential predators, relative to the blind side. We found that Platichthys scales require the greatest puncture force (~2x force for comparably sized individuals) of all three taxa. We also found no significant differences between the eyed and blind sides of any flatfish species. Puncture force scaled directly with body length in two of the three species, but sub-linearly (relative to length) in the third species (Isopsetta isolepis). We hypothesize that, as fish grow larger, scales increase in thickness, and the additional material yields increased resistance to puncture forces. Ongoing studies considering the relationship between body size, scale thickness, and morphology may reveal the physical parameters that underlie differences in the puncture forces among flatfishes.
